Transverse or longitudinal patterned synthetic exchange biasing for stabilizing GMR sensors

ABSTRACT

Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.

RELATED PATENT APPLICATION

[0001] This application is related to Docket No. HT01-032, Serial No.(______) filing date (______), to Docket No. HT01-037, Ser. No.10/077064, filing date Feb. 15, 2002 and to Docket No. HT01-020, SerialNo. (______) filing date (______), assigned to the same assignee as thecurrent invention.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates generally to the fabrication of a giantmagnetoresistive (GMR) magnetic field sensor for a magnetic read head,more specifically to the use of either transverse or longitudinalsynthetic exchange biasing to stabilize, suppress side reading andreduce the magnetic track width (MRW) of such a sensor.

[0004] 2. Description of the Related Art

[0005] Magnetic read heads whose sensors make use of the giantmagnetoresistive effect (GMR) in the spin-valve configuration (SVMR)base their operation on the fact that magnetic fields produced by datastored in the medium being read cause the direction of the magnetizationof one layer in the sensor (the free magnetic layer) to move relative toa fixed magnetization direction of another layer of the sensor (thefixed or pinned magnetic layer). Because the resistance of the sensorelement is proportional to the cosine of the (varying) angle betweenthese two magnetizations, a constant current (the sensing current)passing through the sensor produces a varying voltage across the sensorwhich is interpreted by associated electronic circuitry. The accuracy,linearity and stability required of a GMR sensor places stringentrequirements on the magnetization of its fixed and free magnetic layers.The fixed layer, for example, has its magnetization “pinned” in adirection normal to the air bearing surface of the sensor (thetransverse direction) by an adjacent magnetic layer (typically anantiferromagnetic layer) called the pinning layer. The free layer istypically magnetized in a direction along the width of the sensor andparallel to the air bearing surface (the longitudinal direction). Layersof hard magnetic material (permanent magnetic layers) or laminates ofantiferromagnetic and soft magnetic materials are typically formed oneach side of the sensor and oriented so that their magnetic fieldextends in the same direction as that of the free layer. These layers,called longitudinal bias layers, maintain the free layer as a singlemagnetic domain and also assist in linearizing the sensor response bykeeping the free layer magnetization direction normal to that of thefixed layer when quiescent. Maintaining the free layer in a singledomain state significantly reduces noise (Barkhausen noise) in thesignal produced by thermodynamic variations in domain configurations. Amagnetically stable spin-valve sensor using either hard magnetic biasinglayers or ferromagnetic biasing layers is disclosed by Zhu et al. (U.S.Pat. No. 6,324,037 B1) and by Huai et al. (U.S. Pat. No. 6,222,707 B1).

[0006] The importance of longitudinal bias has led to various inventionsdesigned to improve the material composition, structure, positioning andmethod of forming the magnetic layers that produce it. One form of theprior art provides for sensor structures in which the longitudinal biaslayers are layers of hard magnetic material (permanent magnets) thatabut the etched back ends of the active region of the sensor to producewhat is called an abutted junction configuration. This arrangement fixesthe domain structure of the free magnetic layer by magnetostaticcoupling through direct edge-to-edge contact at the etched junctionbetween the biasing layer and the exposed end of the layer being biased(the free layer). Another form of the present art employs patterneddirect exchange bias. Unlike the magnetostatic coupling resulting fromdirect contact with a hard magnetic material that is used in the abuttedjunction, in exchange coupling the biasing layer is a layer offerromagnetic material which overlays the layer being biased, but isseparated from it by a thin coupling layer of conducting, butnon-magnetic material. This non-magnetic gap separating the two layersproduces exchange coupling between them, a situation in which it isenergetically favorable for the biasing layer and the biased layerassume a certain relative direction of magnetization. Another form ofexchange coupling involves a direct contact between the freeferromagnetic layer and an overlaying layer of antiferromagneticmaterial. Xiao et al. (U.S. Pat. No. 6,322,640 B1) disclose a method forforming a double, antiferromagnetically biased GMR sensor, using as thebiasing material a magnetic material having two crystalline phases, oneof which couples antiferromagnetically and the other of which does not.Fuke et al. (U.S. Pat. No. 6,313,973 B1) provides an exchange coupledconfiguration comprising a coupling film, an antiferromagnetic film anda ferromagnetic film and wherein the coupling film has a particularlyadvantageous crystal structure.

[0007] As the area density of magnetization in magnetic recording media(eg. disks) continues to increase, significant reduction in the width ofthe active sensing region (trackwidth) of read-sensors becomesnecessary. For trackwidths less than 0.2 microns (μm), the traditionalabutted junction hard bias structure discussed above becomes unsuitablebecause the strong magnetostatic coupling at the junction surfaceactually pins the magnetization of the (very narrow) biased layer (thefree layer), making it less responsive to the signal being read and,thereby, significantly reducing the sensor sensitivity.

[0008] Under very narrow trackwidth conditions, the exchange bias methodbecomes increasingly attractive, since the free layer is not reduced insize by the formation of an abutted junction, but extends continuouslyacross the entire width of the sensor element. FIG. 1 is a schematicdepiction of an abutted junction arrangement and FIG. 2 is an equallyschematic depiction of a direct exchange coupled configuration. As canbe seen, the trackwidth in the abutted junction is made narrow byphysically etching away both ends of the sensor, whereas in the exchangecoupled sensor, the trackwidth is defined by placement of the conductiveleads and bias layers while the sensor element retains its full width.

[0009] The direct exchange biasing also has disadvantages when used in avery narrow trackwidth configuration because of the weakness of thepinning field, which is found to be, typically, approximately 250 Oe.The present invention will address this weak pinning field problem whileretaining the advantages of exchange biasing by providing a new exchangebiased configuration, synthetic exchange biasing. In this configuration,the biasing layer is exchange coupled to the free layer byantiferromagnetic exchange coupling, in which the ferromagnetic biasinglayer and the ferromagnetic free layer are coupled by a non-magneticlayer to form a configuration in which the two layers have antiparallelmagnetizations (a synthetic antiferromagnetic layer). A stronger pinningfield, typically exceeding 700 Oe, can be obtained using the syntheticexchange biasing method. More advantageously, an effective magnetictrackwidth of 0.15μm can be obtained with a physical track width of0.1μm by using such a configuration by reducing the level of sidereading (sensor response generated by signals originating outside of themagnetic trackwidth region) which is produced by the portion of the freelayer that is beneath the biasing layer and conduction leads. Theinvention provides such a novel synthetic exchange biased sensor in twoconfigurations, longitudinal and transverse, each of which is shown tohave particular advantages both in its operation and its formation.

SUMMARY OF THE INVENTION

[0010] It is a first object of the present invention to provide amagnetically stable patterned synthetic exchange biased GMR sensorcapable of reading high area density magnetic recordings of densitiesexceeding 60 Gb/in² (gigabits per square inch).

[0011] It is a second object of the present invention to provide such apatterned synthetic exchange biased GMR sensor which is biased in eitherthe longitudinal or the transverse directions.

[0012] It is a third object of the present invention to provide such asynthetic exchange biased GMR sensor having a very narrow effectivemagnetic trackwidth in which undesirable side reading is significantlyreduced.

[0013] It is a fourth object of the present invention to provide such asynthetic exchange biased GMR sensor that is easily fabricated.

[0014] It is a fifth object of the present invention to provide such asynthetic exchange biased GMR sensor that has thin conducting leadlayers for an improved topography.

[0015] The objects of this invention will be achieved in threeembodiments, each of which will now be briefly described and will thenbe described in fuller detail below. In the first embodiment, asynthetic exchange longitudinally biased GMR sensor will be provided,said sensor having a bottom spin valve, specularly reflecting structurewhich can be deposited in a single fabrication process and which has thefollowing structural form:

NiCr/MnPt/CoFe(AP2)/Ru/CoFe(AP1)/Cu/CoFe—NiFe/Ru/CoFe/IrMn/Ta/Au

[0016] The NiCr is a seed layer, the MnPt is an antiferromagneticpinning layer for the bottom synthetic pinned layer ofCoFe(AP2)/Ru/CoFe(AP1), wherein the two ferromagnetic exchange coupledCoFe layers are labeled AP1 & AP2 to distinguish them. The Cu layer is aconducting, non-magnetic spacer layer separating the synthetic pinnedlayer from the CoFe—NiFe ferromagnetic free layer (a bilayer). Thislatter bilayer is antiferromagnetically exchange coupled across a Rulayer to a (patterned) CoFe biasing layer, forming the syntheticexchange coupled bias structure which has both a high pinning field andadvantageous magnetostriction characteristics. The exchange biased layeris itself antiferromagnetically pinned by direct exchange coupling withan antiferromagnetic IrMn layer, over which is a conductive lead layerof Ta/Au. It is found that the pinning field of the free layer providedby the patterned bias layer in this synthetic exchange coupledconfiguration exceeds 650 Oe and may be as high as 755 Oe, as comparedto pinning fields of the order of 250-300 Oe for the direct (notsynthetic) coupled structure.

[0017] In the second embodiment, a synthetic exchange transverselybiased GMR sensor will be provided together with a method for itsfabrication. The structural form of this embodiment is:

NiCr/AFM/CoFe(AP2)/Ru/CoFe(AP1)/Cu/CoFe—NiFe/Ru/CoFe/AFM/Ta/Au.

[0018] The NiCr is a seed layer, AFM denotes an antiferromagneticpinning layer for the bottom synthetic pinned layer of CoFe(AP2)/Ru/CoFe(AP1), wherein the two ferromagnetic exchange coupled CoFelayers are labeled AP1 & AP2 to distinguish them. The Cu layer is aconducting, non-magnetic spacer layer separating the synthetic pinnedlayer from the CoFe—NiFe ferromagnetic free layer (a bilayer). Thislatter bilayer is antiferromagnetically exchange coupled across a Rulayer to a (patterned) CoFe biasing layer, forming the syntheticexchange coupled bias structure. The exchange biased layer is itselfantiferromagnetically pinned by direct exchange coupling with anantiferromagnetic layer, again denoted AFM, over which is a conductivelead layer of Ta/Au. In contrast to the structural form of the firstembodiment, the same antiferromagnetic material, typically either IrMnor MnPt, can serve in both locations designated AFM. An importantadvantage of the transverse biasing is that the magnetic field of thefree and pinned layers are in the same direction, producing a plateauregion under low external field wherein the free layer magnetization andthe pinned layer magnetizations do not rotate relative to each other.This is particularly important for reducing signal contributions fromthe free layer region that is under the biasing layer which thenproduces a narrow effective trackwidth.

[0019] It is another one of the advantages of this second embodimentthat different antiferromagnetic materials are not necessary to achieveits objects because both the synthetic pinned layer,CoFe(AP2)/Ru/CoFe(AP1), and the synthetic bias exchange coupled freelayer, CoFe—NiFe/Ru/CoFe, are magnetized along the same direction. Thisallows antiferromagnetic materials with high blocking temperatures to beutilized which, in turn, allows high pinning fields to be obtained. Thehigh pinning fields minimizes the problems caused by sensor current flowwithin the sensor element and, consequently, current shunting is notrequired and thin conducting lead layers can be used. The thirdembodiment of the present invention provides a transversely biasedsensor as in the second embodiment, but the pinning fields at oppositeends of the free layer are antiparallel to each other. Thisconfiguration affords the additional advantages of stabilizing the biaspoint of the free layer and further minimizing side reading by thesensor. In the description of the three embodiments provided below, thestructures, the processes preferred for their fabrication and theiradvantages, will be more fully described.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The objects, features and advantages of the present invention areunderstood within the context of the description of the preferredembodiment, as set forth below. The description of the preferredembodiment is understood within the context of the accompanying figures,wherein:

[0021]FIG. 1 is a highly schematic diagram of a prior-art abuttedjunction GMR sensor stack having a hard magnetic longitudinal bias layerand conductive lead overlayer in contact with the junction. The diagramis a cross-sectional view of the air bearing surface (ABS) of thesensor. The sensor stack shows only the free layer.

[0022]FIG. 2 is a schematic, ABS view, cross-sectional diagram of aprior-art direct exchange (longitudinally) biased GMR sensor stack,showing the patterned biasing layers, their magnetization directions,and other layers of the sensor.

[0023]FIG. 3a is a schematic, ABS view, cross-sectional diagram of asynthetic exchange (longitudinally) biased GMR sensor stack, beforepatterning, fabricated in accord with the objects of the first preferredembodiment of the present invention.

[0024]FIG. 3b shows the process of patterning the sensor of FIG. 3a.

[0025]FIG. 4a is a schematic, ABS view, cross-sectional diagram of asynthetic exchange biased GMR sensor stack formed in accord with asecond embodiment of the present invention. The transversemagnetizations of the exchange biased free layer and the syntheticpinned layer are indicated.

[0026]FIG. 4b is the sensor stack of FIG. 4a subsequent to patterning.

[0027]FIG. 5a is a schematic, ABS view, cross-sectional diagram of apartially formed synthetic exchange biased GMR sensor stack formed inaccord with a third embodiment of the present invention. In thisembodiment the transverse magnetizations of each lateral end of theexchange biased free layer are antiparallel to each other and each isalso antiparallel to the transverse magnetizations of the biasing layersthat overlay them.

[0028]FIGS. 5b-5 e show the detailed processes by which the sensor stackof 5 a is patterned and magnetized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Referring first to FIG. 1 there is shown a schematiccross-sectional view of the ABS surface of a typical abutted junctionGMR sensor designed in accord with the prior art. As can be seen, thenarrow trackwidth is obtained at the price of reducing the physicalwidth of the ferromagnetic free layer (10). As a result, the biasinglayer (20) pins the magnetization of the free layer and reduces thesensitivity of the sensor.

[0030] Referring next to FIG. 2, there is shown a schematiccross-sectional view of the ABS surface of a patterned direct exchangelongitudinally biased GMR sensor of the prior art. The physicaltrackwidth (10) of this configuration is defined by the width of theregion between the leads (20), typically a Ta/Au bilayer, and thepatterned biasing layers beneath them (25), typically layers of CoFe.The ferromagnetic free layer (27), typically a CoFe/NiFe bilayer,extends the entire width of the sensor so it is not adversely affectedby the edge pinning field of the biasing layer, which is a disadvantageof the hard biased abutted junction of FIG. 1. The diagram also showsthe antiferromagnetic layer (29), typically a layer of IrMn, which pinsthe patterned biasing layer (25). The free layer (27) is separated fromthe biasing layer (25) by a non-magnetic coupling layer (28) which istypically a layer of Cu or Ru and which directly exchange couples theferromagnetic free layer (27) to the ferromagnetic biasing layer (25) byferromagnetic coupling to produce parallel magnetizations (11) labeledM2 (biasing layer) and M1 (free layer). The remainder of theconfiguration comprises an antiferromagnetically coupled (synthetic)pinned layer (30), which comprises two ferromagnetic layers ((32) and(34)) antiferromagnetically exchange coupled across a non-magneticcoupling layer (36) and which is separated from (27) by a non magneticspacer layer (31). Beneath (30) there is an antiferromagnetic pinninglayer (40), typically a layer of MnPt, which pins theantiferromagnetically coupled pinned layer. The magnetic moments of theantiferromagnetically coupled pinned layers are in the transversedirection (perpendicular to the plane of the figure) and areantiparallel, with the directions of magnetization of the individuallayers indicated by circles (15) (out of the plane) and crosses withincircles (17) (into the plane). Obtaining perpendicularity of the freelayer magnetization and pinned layer magnetization complicates thefabrication process of the sensor, since two different antiferromagneticmaterials with different blocking temperatures are typically requiredfor (40) and (29), eg. IrMn and MnPt in this illustration, as aredifferent annealing schedules so that the magnetization of the pinnedlayer should not affect the magnetization of the biasing layer. When thephysical trackwidth (10) of this entire configuration is narrow,however, (less than 0.2 microns) the strength of the ferromagneticcoupling (the pinning field) is weak and is typically less than 250 Oe.Note that thicknesses are not given for this figure since theconfiguration is shown for comparison purposes only.

[0031] First Preferred Embodiment

[0032] Referring next to FIG. 3a, there is shown a schematiccross-sectional view of the air bearing surface (ABS) of a syntheticexchange longitudinally biased GMR sensor, before patterning, fabricatedin accord with the objects of a first embodiment of the presentinvention and having the properties and advantages of said embodiment.The device is fabricated in a sequence of three major steps: 1)depositing the sensor layers; 2) annealing and magnetizing the syntheticpinned layer and the synthetic biased free layer; 3) patterning.

[0033] 1) Deposition Process

[0034] First there is deposited a seed layer (9), which is typically alayer of NiCr deposited to a thickness of between approximately 55 and65 angstroms with 60 angstroms being preferred. On this seed layer isthen deposited a first antiferromagnetic layer (40) to serve as apinning layer. Typically this pinning layer is a layer of MnPt depositedto a thickness of between approximately 80 and 150 angstroms with 100angstroms being preferred. On the pinning layer, and pinned by it, thereis then formed a synthetic antiferromagnetic pinned layer (30), which isan antiferromagnetically coupled trilayer comprising a firstferromagnetic layer (32), a first non-magnetic antiferromgneticallycoupling layer (36) formed on (32) and a second ferromagnetic layer (34)formed on the coupling layer. The ferromagnetic layers are typicallylayers of CoFe, with the first layer having a thickness of betweenapproximately 12 and 20 angstroms with 15 angstroms being preferred andthe second layer having a thickness of between approximately 15 and 25angstroms with 20 angstroms being preferred. The coupling layer, whichis typically a layer of Ru, is formed to a thickness of betweenapproximately 7 and 9 angstroms with 7.5 angstroms being preferred. Onthe synthetic pinned layer is then formed a non-magnetic spacer layer(31), which separates the pinned and free layers. This spacer layer istypically a layer of Cu, which is formed to a thickness of betweenapproximately 13 and 25 angstroms with 18 angstroms being preferred. Thefree layer (27), which is a ferromagnetic bilayer of CoFe (22) and NiFe(23), is then formed on the spacer layer, wherein the CoFe layer has athickness of between approximately 5 and 15 with 10 angstroms beingpreferred and the NiFe layer has a thickness of between approximately 15and 30 angstroms with 20 angstroms being preferred. The free layer isthen antiferromagnetically exchange coupled across a non HTO magneticcoupling layer (28) to a ferromagnetic biasing layer (25), forming,thereby, the synthetic exchange biased configuration (26). The couplinglayer in this case is a layer of Ru of thickness between approximately 7and 9 angstroms with 7.5 angstroms being preferred and the biasing layeris a layer of CoFe of thickness between approximately 10 and 25angstroms with 15 angstroms being preferred. The synthetic exchangebiased configuration (26) is then pinned by an antiferromagnetic layerof IrMn (29) of thickness between approximately 35 and 55 angstroms with40 angstroms being preferred. A conducting lead layer (20) is depositedover the IrMn layer in a lead overlay (LOL) configuration. The leadlayer is typically a Ta/Au bilayer of thickness between approximately100 and 500 angstroms.

[0035] 2) Annealing Process

[0036] The GMR sensor configuration thus formed is then given a firstpinned layer annealing to fix the magnetizations of both syntheticpinned layers (30) & (26). The anneal consists of a 5 hour 280° C.anneal in an external transversely directed magnetic field ofapproximately 10 kOe (kilo-oersteds) to set both pinned layers in thetransverse direction (perpendicular to the air-bearing surface). Theresulting magnetization vectors are shown only for the first pinnedlayer (30) as a circle (15), representing a direction out of the plane,and a circle with an interior cross (17), representing a direction intothe plane. Following this first pinned layer anneal, a second anneal isapplied at a lower temperature and lower magnetic field to reset themagnetization of the synthetic exchange biased layer (26) from thetransverse direction into the longitudinal direction. This second annealis carried out for a time of approximately 30 minutes at an annealingtemperature of approximately 250° C., which is higher than the IrMnblocking temperature. The resulting magnetizations are shown as arrows,M1 (12) being the magnetization of the free layer and M2 (11) that ofthe biasing layer. Under this aimeal, the synthetic pinned layer (30 )retains its transverse magnetization. It is found by experiment that theconfiguration described above, under the sequence of anneals to which itis subjected as is also described above, has the advantageous propertiesof a high pinning field that is approximately 755 Oe, as well as adesirable value of free layer magnetostriction.

[0037] 3) Patterning Process

[0038] Referring now to FIG. 3b, there is shown a schematic diagramillustrating the process by which a physical trackwidth (10) ofapproximately 0.1 microns is formed in the sensor of FIG. 3a by etchingthe lead and pinning layers to form the patterned exchange structure.Patterning is done by sequentially removing the entire thickness of alateral portion of the lead layer (40) (shown in dashed outline) and theentire thickness of the IrMn pinning layer beneath it (42) (shown indashed outline) by use of a reactive ion etch (RIE) or an ion beam etch(IBE). Removal of these two layers exposes a portion of the CoFe biasinglayer (44), said portion then being effectively removed by an oxidationprocess, which converts it to a non-magnetic CoFeO (shown shaded). Inthis process, the antiferromagnetically coupling layer (28) of Ru actsas an oxidation barrier to prevent the oxidation from extending downwardto adversely affect the ferromagnetic free layer (27). The surface ofthe coupling layer (28) beneath (44) is thereby itself oxidized at thetermination of the process. Note in the synthetic pinned layer (30) thatsmall circles (15) represent magnetizations out of the plane, circleswith interior crosses (17) are into the plane. The symbols M1 (12) andM2 (11) refer to the antiparallel directions of the magnetizations ofthe free (M1) and pinning (M2) layers.

[0039] Second Preferred Embodiment

[0040] Referring next to FIG. 4a, there is shown a schematiccross-sectional view of the air bearing surface (ABS) of a syntheticexchange transversely biased GMR sensor, before patterning, fabricatedin accord with the objects of a second embodiment of the presentinvention and having the properties and advantages of said embodiment.The device is fabricated in a sequence of three major steps: 1)depositing the sensor layers; 2) annealing and magnetizing the syntheticpinned layer and the synthetic biased free layer; 3) patterning.

[0041] 1) Deposition Process

[0042] First there is deposited a seed layer (9), which is typically alayer of NiCr deposited to a thickness of between approximately 50 and60 angstroms. On this seed layer is then deposited a firstantiferromagnetic layer (40) to serve as a pinning layer. Typically thispinning layer is a layer of MnPt deposited to a thickness of betweenapproximately 100 and 150 angstroms, but other anti ferromagneticmaterials such as NiMn, PdPtMn, FeMn or IrMn can be used. On the firstpinning layer, and to be pinned by it, there is then formed a syntheticantiferromagnetic pinned layer (30), which is an antiferromagneticallycoupled trilayer comprising a first ferromagnetic layer (32), a firstnon-magnetic antiferromagnetically coupling layer (36) formed on (32)and a second ferromagnetic layer (34) formed on the coupling layer. Theferromagnetic layers are typically layers of CoFe, with the firstferromagnetic layer having a thickness of between approximately 15 and20 angstroms with 15 angstroms being preferred and the secondferromagnetic layer having a thickness of between approximately 20 and25 angstroms with 20 angstroms being preferred. The first couplinglayer, which can be a layer of Ru, is formed to a thickness of betweenapproximately 7 and 9 angstroms with 7.5 angstroms being preferred.Alternatively, the first coupling layer can be a layer of Rh, formed toa thickness of between 4 and 6 angstroms with 5 angstroms beingpreferred. On the synthetic antiferromagnetic pinned layer there is thenformed a non-magnetic spacer layer (31), which separates the pinned andfree layers. This spacer layer is typically a layer of Cu, which isformed to a thickness of between approximately 15 and 22 angstroms with18 angstroms being preferred. The free layer (27), which is preferably aferromagnetic bilayer of CoFe (22) and NiFe (23), is then formed on thespacer layer, wherein the CoFe layer has a thickness of betweenapproximately 5 and 15 with 10 angstroms being preferred and the NiFelayer has a thickness of between approximately 15 and 30 angstroms with20 angstroms being preferred. The free layer is thenantiferromagnetically exchange coupled across a second non-magneticcoupling layer (28) to a ferromagnetic biasing layer (25), forming,thereby, the synthetic exchange biased configuration (26). If the firstnon-magnetic coupling layer (36) is a layer of Ru, then the secondnon-magnetic coupling layer (28) is also a layer of Ru of thicknessbetween approximately 7 and 8 angstroms with 7.5 angstroms beingpreferred. If the first coupling layer is a layer of Rh, then the secondcoupling layer is also a layer of Rh of a thickness between 4 and 6angstroms with 5 angstroms being preferred. If the second coupling layeris Ru, the biasing layer (25) is a layer of CoFe of thickness betweenapproximately 15 and 30 angstroms with 15 angstroms being preferred. Ifthe second coupling layer is Rh, the biasing layer (25) is a layer ofCoFe of thickness between approximately 25 and 30 angstroms with 28angstroms being preferred. It is to be noted that the thicker biasinglayer (25) formed in conjunction with the Rh coupling layer produces agreater pinning field in the sensor.

[0043] The synthetic exchange biased configuration (26) is then pinnedby a second pinning layer, which is an antiferromagnetic layer of MnPt(25) of thickness between approximately 80 and 100 angstroms with 100angstroms being preferred (note, if any of the other antiferromagneticmaterials mentioned above have been used to form the first pinninglayer, that same material can also be used here to form the secondpinning layer). A conducting lead layer (20) is deposited over the MnPtlayer (25) in a lead overlay (LOL) configuration. The lead layer istypically a Ta/Au/Ta trilayer of thickness between approximately 200 and400 angstroms.

[0044] 2) Annealing Process

[0045] The GMR sensor configuration thus formed is then given a pinnedlayer annealing to fix the magnetization of both synthetic pinned layers(26) & (30), which are, respectively, the antiferromagnetic pinned layerand the synthetic exchange biased configuration. The anneal consists ofa 5 hour 280° C. anneal in an external magnetic field of approximately10 kOe (kilo-oersteds) to set both pinned layers in the transversedirection (perpendicular to the air-bearing surface). The resultingmagnetization vectors are shown as circles (53 & 57) representingmagnetizations out of the plane, and circles with interior crosses (51 &55) representing magnetizations into the plane. M1 and M2 are the labelsrepresenting the magnetizations of the free and biasing layersrespectively. It is found by experiment that the configuration describedabove, under the anneal to which it is subjected as is also describedabove, has the advantageous properties of a high pinning field that ismore than 1000 Oe, as well as an effective trackwidth of less than 0.15microns subsequent to the patterning that will now be described. Asignificant advantage of the transverse directions of both the free andpinned layers is that there is a plateau of very little relativerotation of their magnetizations under small external magnetic fields.This plateau is particularly important in the region of the free layerdirectly beneath the biasing layer in that it leads to extremely smallsignals being produced by this portion of the free layer. Since unwantedside reading is a direct result of signals emanating from the extremelateral portions of the free layer, this diminution of signals from thatportion is directly responsible for the narrow effective trackwidth.Another important advantage of the transverse directions of both thefree and pinned layers is that it is unnecessary to rotate the freelayer magnetization with a second anneal after fixing the magnetizationof the pinned layer. This allows the use of antiferromagnetic pinninglayers of the same high blocking temperature material to be used to pinboth the synthetic pinned layer and the synthetic exchange biased freelayer. In turn, this allows high external fields to be used to fix thepinning field, which increases the efficacy of the biasing layer andreduces the effective trackwidth of the sensor. It has also beendemonstrated that the high pinning fields thus obtained (exceeding 1000Oe) eliminate the need for current shunting of the sensor current, whichpermits the use of thinner conducting lead layers and provides a moreadvantageous topology.

[0046] 3) Patterning Process

[0047] Referring now to FIG. 4b, there is shown a schematic diagramillustrating the process by which a physical trackwidth (10) ofapproximately 0.1 microns is formed in the sensor of FIG. 4a bypatterning the lead and pinning layers to form the patterned exchangestructure. Patterning is done by sequentially removing the entirethickness of a lateral portion of the lead layer ((40) shown in dashedoutline) and the entire thickness of the MnPt pinning layer beneath it((42) shown in dashed outline) by use of a reactive ion etch (RIE) or anion beam etch (IBE). Removal of these two layers exposes the CoFebiasing layer ( 42 ), the portion of which is exposed ((44) shownshaded) being then effectively removed by an oxidation process, whichconverts it to non-magnetic CoFeO. In this process, theantiferromagnetically coupling layer (28) of Ru (or Rh) acts as anoxidation barrier to prevent the oxidation from extending downward tothe ferromagnetic free layer (27) and adversely affecting it. Theexposed surface of the coupling layer (28) is thereby itself oxidized atthe termination of the process.

[0048] Third Preferred Embodiment

[0049] Referring next to FIG. 5a, there is shown a schematiccross-sectional view of the air bearing surface (ABS) of a partiallyfabricated synthetic exchange transversely biased GMR sensor, before theantiparallel magnetization of its biasing layer and before deposition ofa conducting lead layer and final patterning, fabricated in accord withthe objects of a third embodiment of the present invention and havingthe properties and advantages of said embodiment. In this embodiment thetransverse magnetizations of the pinning layer and free layer areantiparallel to each other at the opposite ends of the sensor where theyare beneath the conducting lead layers. This configuration has beenshown to have two advantages: 1) prevention of the bias point shift atthe center active region of the free layer and 2) minimization of sidereading at both sides of the sensor element.

[0050] The device is fabricated in a sequence of four steps: 1)depositing the sensor layers up to and including the exchange biasinglayer (shown in FIG. 5a); 2) separately magnetizing both lateral ends ofthe exchange biasing layer in opposite transverse directions using atwo-step patterning and annealing sequence (shown in FIGS. 5b and 5 c);3) depositing conducting lead layers (shown in FIG. 5d); 4) patterning(FIG. 5d).

[0051] 1) Deposition Process

[0052] Referring to FIG. 5a and looking vertically upward, there isfirst seen deposited a seed layer (9), which is typically a layer ofNiCr deposited to a thickness of between approximately 50 and 60angstroms. On this seed layer is then deposited a firstantiferromagnetic layer (40) to serve as a pinning layer. Typically thispinning layer is a layer of MnPt deposited to a thickness of betweenapproximately 100 and 150 angstroms, but other antiferromagneticmaterials such as NiMn, PdPtMn, FeMn or IrMn can be used. On the firstpinning layer there is then formed a synthetic antiferromagnetic pinnedlayer (30), which is an antiferromagnetically coupled trilayercomprising a first ferromagnetic layer (32), a first non-magneticantiferromagnetically coupling layer (36) formed on (32) and a secondferromagnetic layer (34) formed on the coupling layer. The ferromagneticlayers are typically layers of CoFe, with the first ferromagnetic layerhaving a thickness of between approximately 15 and 20 angstroms with 15angstroms being preferred and the second ferromagnetic layer having athickness of between approximately 20 and 25 angstroms with 20 angstromsbeing preferred. The first non-magnetic antiferromagnetically couplinglayer, which can be a layer of Ru, is formed to a thickness of betweenapproximately 7 and 9 angstroms with 7.5 angstroms being preferred.Alternatively, the first coupling layer can be a layer of Rh, formed toa thickness of between 4 and 6 angstroms with 5 angstroms beingpreferred. In either case, the layer is formed of a material and to athickness that will cause the two ferromagnetic layers to align theirmagnetizations in an antiparallel direction upon annealing. On thesynthetic pinned layer there is then formed a non-magnetic spacer layer(31), which separates the pinned and free layers. This spacer layer istypically a layer of Cu, which is formed to a thickness of betweenapproximately 15 and 22 angstroms with 18 angstroms being preferred. Thefree layer (27), which in this preferred embodiment is a ferromagneticbilayer of CoFe (22) and NiFe (23), is then formed on the spacer layer,wherein the CoFe layer has a thickness of between approximately 5 and 15with 10 angstroms being preferred and the NiFe layer has a thickness ofbetween approximately 15 and 30 angstroms with 20 angstroms beingpreferred. The free layer is then antiferromagnetically exchange coupledacross a second non-magnetic coupling layer (28) to a ferromagneticbiasing layer (25), forming, thereby, the synthetic antiferromagneticexchange biased configuration (26). If the first non-magnetic couplinglayer (36) is a layer of Ru, then the second non-magnetic coupling layer(28) is also a layer of Ru of thickness between approximately 7 and 8angstroms with 7.5 angstroms being preferred. If the first couplinglayer is a layer of Rh, then the second coupling layer is also a layerof Rh of a thickness between 4 and 6 angstroms with 5 angstroms beingpreferred. If the second coupling layer is Ru, the biasing layer (25) isa layer of CoFe of thickness between approximately 15 and 30 angstromswith 15 angstroms being preferred. If the second coupling layer is Rh,the biasing layer (25) is a layer of CoFe of thickness betweenapproximately 25 and 30 angstroms with 28 angstroms being preferred. Itis to be noted that the thicker biasing layer (25) formed in conjunctionwith the Rh coupling layer produces a greater pinning field in thesensor. At this point in the fabrication process the magnetization ofthe pinned layer can be set by an anneal in the same manner as in theprevious embodiments. A 5 hour anneal in a 10 kOe magnetic field at atemperature of 280° C. is preferred.

[0053] Referring now to FIG. 5b, there is shown an upper portion of thestructure of FIG. 5a wherein a lateral portion (60) of the ferromagneticbiasing layer (25) has been covered by a layer of etch resistantmaterial (62) (such as photoresist), leaving the remaining portion(shown shaded) of the biasing layer uncovered (64). This uncoveredportion is then cleaned by a sputter etch process.

[0054] Referring next to FIG. 5c, there is shown the cleaned portion(64) refilled with the same ferromagnetic material of the biasing layerand covered by an additional layer of antiferromagnetic material (66),such as a layer of IrMn deposited to a thickness Of betweenapproximately 35 and 55 angstroms with 40 angstroms being preferred, toact as a pinning layer. During this deposition process, the fabricationthus produced is annealed in a first transverse magnetic field in afirst transverse direction to fix the direction of the magnetizations inthe antiferromagnetic coupling between the portion of the biasing layer(64), whose magnetization is shown as a circle (68), and thecorresponding portion of the free layer (27) beneath it, whoseantiparallel magnetization is shown as a circle with a cross (69). Thefirst anneal is for between approximately 30 and 60 minutes but whereapproximately 30 minutes is preferred, at a temperature of betweenapproximately 250° C. and 280° C., but where 250° C. is preferred andwith a magnetic field of between approximately 250 and 500 Oe but where250 Oe is preferred. The antiferromagnetic layer (66) pins the biasinglayer in this process.

[0055] Referring next to FIG. 5d, there is shown the fabrication of FIG.5c, wherein the surface of the opposite lateral portion (72) of thebiasing layer is now exposed, while the remainder of the layer, whichhas already been magnetized, is covered by a resistant layer (74), suchas a layer of photoresist. In a similar fashion to that described inFIG. 5c, the portion (72) is cleaned and covered with additional biasingmaterial and, over it, a layer of antiferromagnetic pinning material(75) such as IrMn is formed in a manner identical to that described inFIG. 5c. During the deposition process a second external magnetic fieldin the opposite direction to that used in the process of FIG. 5c isapplied and the biasing layer portion (72) is thereby magnetized in thedirection of that magnetic field (circle with a cross (81)) and the freelayer beneath it (27) is oppositely magnetized (circle (83)). The secondanneal, like the first, is for between approximately 30 and 60 minutesbut where approximately 30 minutes is preferred, at a temperature ofbetween approximately 250° C. and 280° C., but where 250° C. ispreferred and with a magnetic field of between approximately 250 and 500Oe but where 250 Oe is preferred. The deposited antiferromagnetic layer(75) serves to pin the biasing layer by this process.

[0056] Referring now to FIG. 5e, there is shown the fabrication of FIG.5d wherein a central portion (85) of the twice magnetized biasing layeris removed by an ion beam or chemical etching process to form atrackwidth of desired dimension. A conducting lead layer (90) has beenformed over the two biasing layers. The lead layer is typically aTa/Au/Ta trilayer of thickness between approximately 200 and 400angstroms.

[0057] As is understood by a person skilled in the art, the preferredembodiments of the present invention are illustrative of the presentinvention rather than limiting of the present invention. Revisions andmodifications may be made to methods, materials, structures anddimensions employed in fabricating a synthetic, patterned,longitudinally or transversely exchange biased GMR sensor with narroweffective trackwidth, while still providing a method for fabricatingsuch a synthetic, patterned, longitudinally or transversely exchangebiased GMR sensor with narrow effective trackwidth, in accord with thespirit and scope of the present invention as defined by the appendedclaims.

What is claimed is:
 1. A patterned, synthetic longitudinally exchangebiased GMR sensor with narrow effective trackwidth comprising: asubstrate; a seed layer; a first layer of antiferromagnetic materialformed on the seed layer, said layer being a first antiferromagneticpinning layer; a synthetic antiferromagnetic pinned layer formed on saidfirst antiferromagnetic pinning layer, the magnetization of said pinnedlayer being pinned by exchange coupling to said first antiferromagneticpinning layer; a non-magnetic spacer layer formed on said pinned layer;a ferromagnetic free layer formed on said non-magnetic spacer layer; anon-magnetic antiferromagnetically coupling layer formed on saidferromagnetic free layer; a longitudinal biasing layer formed on saidcoupling layer, said biasing layer being formed as two discrete,disconnected and laterally separated ferromagnetic segments, laterallyand symmetrically disposed to either side of the antiferromagneticallycoupling layer and wherein said segments are separated by a portion ofsaid biasing layer which has been rendered non-magnetic and defines aphysical trackwidth and wherein the ferromagnetic segments of saidbiasing layer are antiferromagnetically exchange coupled to said freelayer through said antiferromagnetically coupling layer to form asynthetic antiferromagnetic exchange biased configuration; a patternedantiferromagnetic pinning layer formed as two separate, disconnectedsegments, wherein a segment is formed on each ferromagnetic segment ofsaid patterned, longitudinal biasing layer and is coexstensive with saidsegment, and wherein each of said patterned antiferromagnetic layersegments is exchange coupled to said longitudinal biasing layer segment;a conductive lead layer formed on said antiferromagnetic layer andcoextensive with it.
 2. The sensor of claim 1 wherein the first andsecond antiferromagnetic layers are chosen from the group ofantiferromagnetic materials consisting of PtMn, IrMn, NiMn, PdPtMn andFeMn.
 3. The sensor of claim 1 wherein the first antiferromagnetic layeris a layer of PtMn and is formed to a thickness of between approximately80 and 150 angstroms, but preferably approximately 100 angstroms.
 4. Thesensor of claim 1 wherein the synthetic antiferromagnetic pinned layeris a trilayer comprising a first and second ferromagnetic layerseparated by a non-magnetic antiferromagnetically coupling layer andwherein the magnetizations of said first and second ferromagnetic layersare antiparallel and transversely oriented.
 5. The sensor of claim 4wherein the first and second ferromagnetic layers are layers offerromagnetic material chosen from the group consisting of CoFe, NiFeand CoFeNi.
 6. The sensor of claim 4 wherein the non-magneticantiferromagnetically coupling layer is a layer of Ru formed to athickness of between approximately 7 and 9 angstroms but whereapproximately 7.5 angstroms is preferred.
 7. The sensor of claim 4wherein the synthetic antiferromagnetic pinned layer is a trilayercomprising a first layer of CoFe, formed to a thickness of betweenapproximately 12 and 20 angstroms with 15 angstroms being preferred anda second layer of CoFe formed to a thickness of between approximately 15and 25 angstroms with 20 angstroms being preferred, with a layer of Rubetween said layers of thickness between approximately 7 and 9 angstromswith approximately 7.5 angstroms being preferred.
 8. The sensor of claim1 wherein the non-magnetic spacer layer is a layer of Cu formed to athickness of between approximately 13 and 25 angstroms, whereapproximately 18 angstroms is preferred.
 9. The sensor of claim 1wherein the ferromagnetic free layer is a layer of ferromagneticmaterial chosen from the group consisting of CoFe, NiFe, andcombinations thereof.
 10. The sensor of claim 1 wherein theferromagnetic free layer is a bilayer comprising a first ferromagneticlayer on which is formed a second ferromagnetic layer wherein said firstferromagnetic layer is a layer of ferromagnetic material chosen from thegroup consisting of CoFe, NiFe, and combinations thereof and whereinsaid second ferromagnetic layer is a layer of ferromagnetic materialchosen from the group consisting of CoFe, NiFe, and combinationsthereof.
 11. The sensor of claim 11 wherein the ferromagnetic free layeris a bilayer comprising a layer of CoFe of thickness betweenapproximately 5 and 15 angstroms, where 10 angstroms is preferred, onwhich is formed a layer of NiFe of thickness between approximately 15and 30 angstroms, where approximately 20 angstroms is preferred.
 12. Thesensor of claim 1 wherein the non-magnetic antiferromagneticallycoupling layer is a layer of Ru formed to a thickness of between 7 and 9angstroms, where approximately 7.5 angstroms is preferred.
 13. Thesensor of claim 12 wherein the patterned ferromagnetic longitudinalbiasing layer is a layer of CoFe formed to a thickness betweenapproximately 10 and 25 angstroms with 15 angstroms being preferred andwherein said biasing layer and said ferromagnetic free layer areantiferromagnetically coupled by said antiferromagnetically coup linglayer and the magnetizations of said biasing layer and saidferromagnetic free layer are antiparallel and longitudinally oriented.14. The sensor of claim 13 wherein the patterned antiferromagneticpinning layer is a layer of IrMn formed to a thickness betweenapproximately 35 and 55 angstroms, where approximately 40 angstroms ispreferred.
 15. The sensor of claim 1 wherein the seed layer is a layerof NiCr formed to a thickness of between approximately 50 and 65angstroms, but where approximately 60 angstroms is preferred.
 16. Amethod for fabricating a patterned, synthetic longitudinally exchangebiased GMR sensor with narrow effective trackwidth comprising: providinga substrate; forming a seed layer on said substrate; forming a firstlayer of antiferromagnetic material on the seed layer, said layer ofantiferromagnetic material being a pinning layer; forming a syntheticantiferromagnetic pinned layer on said first antiferromagnetic pinninglayer; forming a non-magnetic spacer layer on said pinned layer; forminga ferromagnetic free layer on said non-magnetic spacer layer; forming anon-magnetic antiferromagnetically coupling layer on said ferromagneticfree layer; forming a ferromagnetic, longitudinal biasing layer on saidcoupling layer, whereby said free layer, coupling layer and biasinglayer comprise a synthetic antiferromagnetic configuration; forming asecond antiferromagnetic pinning layer on said longitudinal biasinglayer; forming a conductive lead layer on said antiferromagnetic layer;annealing the resulting structure with a first anneal for a firstannealing time, at a first annealing temperature and in a first externalmagnetic field; annealing the resulting structure with a second annealfor a second annealing time, at a second annealing temperature and in asecond external magnetic field; removing, by an etching process, acentral portion of said conductive lead layer and the portion of saidsecond antiferromagnetic pinning layer directly beneath said centralportion, exposing, thereby, an upper surface of said longitudinalbiasing layer beneath said pinning layer and forming, thereby, twodiscrete, disconnected and laterally separated segments, laterally andsymmetrically disposed to either side of said longitudinal biasing layerand separated by the desired physical trackwidth of said sensor;oxidizing the portion of the ferromagnetic longitudinal biasing layerwhose said upper surface has been exposed, said oxidation extending theentire width and thickness of said portion and destroying, thereby, theferromagnetic properties of said layer within said oxidized portion andsaid oxidation being stopped by the upper surface of said non-magneticantiferromagnetically coupling layer.
 17. The method of claim 16 whereinthe seed layer is a layer of NiCr formed to a thickness of betweenapproximately 50 and 65 angstroms but where approximately 60 angstromsis preferred.
 18. The method of claim 16 wherein the first and secondantiferromagnetic layers are chosen from the group of antiferromagneticmaterials consisting of MnPt, IrMn, NiMn, PdPtMn and FeMn.
 19. Themethod of claim 17 wherein the first antiferromagnetic layer is a layerof MnPt and is formed to a thickness of between approximately 50 and 65angstroms, but preferably approximately 100 angstroms.
 20. The method ofclaim 16 wherein the synthetic antiferromagnetic pinned layer is atrilayer comprising a first ferromagnetic layer, a non-magneticantiferromagnetically coupling layer formed on said first layer and asecond ferromagnetic layer formed on said coupling layer.
 21. The methodof claim 20 wherein the first and second ferromagnetic layers are layersof ferromagnetic material chosen from the group consisting of CoFe, NiFeand CoFeNi.
 22. The method of claim 20 wherein the non-magneticantiferromagnetically coupling layer is a layer of Ru.
 23. The method ofclaim 22 wherein the first ferromagnetic layer i s a layer of CoFe,formed to a thickness of between approximately 12 and 20 angstroms with15 angstroms being preferred, the second ferromagnetic layer is a layerof CoFe formed to a thickness of between approximately 15 and 25angstroms with 20 angstroms being preferred, and theantiferromagnetically coupling layer of Ru is formed to a thicknessbetween approximately 7 and 9 angstroms with approximately 7.5 angstromsbeing preferred.
 24. The method of claim 16 wherein the non-magneticspacer layer is a layer of Cu formed to a thickness of betweenapproximately 13 and 25 angstroms, where approximately 18 angstroms ispreferred.
 25. The method of claim 16 wherein the ferromagnetic freelayer is a layer of ferromagnetic material chosen from the groupconsisting of CoFe, NiFe, alloys thereof and laminates thereof.
 26. Themethod of claim 16 wherein the first ferromagnetic layer is formed as abilayer comprising a first ferromagnetic layer of CoFe of thicknessbetween approximately 5 and 15 angstroms, but where 10 angstroms ispreferred, on which is formed a second ferromagnetic layer of NiFe ofthickness between approximately 15 and 30 angstroms, but whereapproximately 20 angstroms is preferred.
 27. The method of claim 16wherein the non-magnetic antiferromagnetically coupling layer is a layerof Ru formed to a thickness of between approximately 7 and 9 angstroms,but where approximately 7.5 angstroms is preferred.
 28. The method ofclaim 29 wherein the ferromagnetic biasing layer is a layer of CoFeformed to a thickness between approximately 10 and 25 angstroms withapproximately 15 angstroms being preferred.
 29. The method of claim 28wherein the second antiferromagnetic layer is a layer of IrMn formed toa thickness between approximately 35 and 55 angstroms, withapproximately 40 angstroms being preferred.
 30. The method of claim 16wherein the first anneal sets the magnetization of the syntheticantiferromagnetic pinned layer to the transverse direction, which is thedirection perpendicular to the air bearing surface of the sensor. 31.The method of claim 32 wherein the first anneal is for betweenapproximately 3 and 6 hours but where approximately 5 hours ispreferred, at a temperature of between approximately 250° C. and 280° C.but where 280° C. is preferred and with a magnetic field of betweenapproximately 6 kOe and 12 kOe, but where approximately 10 kOe ispreferred.
 32. The method of claim 16 wherein the second annealantiferromagnetically couples the ferromagnetic free layer to thelongitudinal bias layer and sets its magnetization in the longitudinaldirection creating, thereby, a synthetic, longitudinally biased exchangecoupled configuration.
 33. The method of claim 32 wherein the secondanneal is for between approximately 30 and 60 minutes but whereapproximately 30 minutes is preferred, at a temperature of betweenapproximately 250° C. and 280° C., but where approximately 250° C. ispreferred and with a magnetic field of between approximately 250 and 500Oe but where approximately 250 Oe is preferred.
 34. A patterned,synthetic transversely exchange biased GMR sensor with narrow effectivetrackwidth comprising: a substrate; a seed layer; a first layer ofantiferromagnetic material formed on the seed layer, saidantiferromagnetic layer being a pinning layer; a syntheticantiferromagnetic pinned layer formed on said first antiferromagneticpinning layer; a non-magnetic spacer layer formed on said pinned layer;a ferromagnetic free layer formed on said non-magnetic spacer layer; anon-magnetic antiferromagnetically coupling layer formed on saidferromagnetic free layer; a transversely biasing layer formed on saidcoupling layer, said biasing layer being formed as two discrete,disconnected and laterally separated ferromagnetic segments, laterallyand symmetrically disposed to either side of the antiferromagneticallycoupling layer and wherein said segments are separated by a portion ofsaid biasing layer which has been rendered non-magnetic and defines aphysical trackwidth and wherein the ferromagnetic segments of saidbiasing layer are antiferromagnetically exchange coupled to said freelayer through said antiferromagnetically coupling layer to form asynthetic antiferromagnetic exchange biased configuration; a patternedantiferromagnetic pinning layer formed as two separate, disconnectedsegments, wherein a segment is formed on each ferromagnetic segment ofsaid patterned, transversely biasing layer and is coexstensive with saidsegment, and wherein each of said patterned antiferromagnetic layersegments is exchange coupled to said transversely biasing layer segment;a conductive lead layer formed on said antiferromagnetic layer andcoextensive with it.
 35. The sensor of claim 34 wherein the first andsecond antiferromagnetic layers are layers of the same antiferromagneticmaterial and said material is chosen from the group of antiferromagneticmaterials consisting of MnPt, IrMn, NiMn, PdPtMn and FeMn.
 36. Thesensor of claim 34 wherein the first antiferromagnetic layer is a layerof MnPt and is formed to a thickness of between approximately 80 and 150angstroms, but preferably approximately 100 angstroms.
 37. The sensor ofclaim 34 wherein the synthetic antiferromagnetic pinned layer is atrilayer comprising a first and second ferromagnetic layer separated bya non-magnetic antiferromagnetically coupling layer and wherein themagnetizations of said first and second ferromagnetic layers areantiparallel and transversely oriented.
 38. The sensor of claim 37wherein the first and second ferromagnetic layers are layers offerromagnetic material chosen from the group consisting of CoFe, NiFeand CoFeNi.
 39. The sensor of claim 37 wherein the non-magneticantiferromagnetically coupling layer is a layer of Ru or a layer of Rh.40. The sensor of claim 37 wherein the synthetic antiferromagneticpinned layer is a trilayer comprising a first layer of CoFe, formed to athickness of between approximately 12 and 20 angstroms with 15 angstromsbeing preferred and a second layer of CoFe formed to a thickness ofbetween approximately 15 and 25 angstroms with 20 angstroms beingpreferred, with a layer of Ru between said layers of thickness betweenapproximately 7 and 9 angstroms with approximately 7.5 angstroms beingpreferred.
 41. The sensor of claim 37 wherein the syntheticantiferromagnetic pinned layer is a trilayer comprising a first layer ofCoFe, formed to a thickness of between approximately 12 and 20 angstromswith 15 angstroms being preferred and a second layer of CoFe formed to athickness of between approximately 15 and 25 angstroms with 20 angstromsbeing preferred, with a layer of Rh between said layers of thicknessbetween approximately 4 and 6 angstroms with approximately 5 angstromsbeing preferred.
 42. The sensor of claim 34 wherein the non-magneticspacer layer is a layer of Cu formed to a thickness of betweenapproximately 13 and 25 angstroms, with approximately 18 angstroms beingpreferred.
 43. The sensor of claim 34 wherein the ferromagnetic freelayer is a layer of ferromagnetic material chosen from the groupconsisting of CoFe, NiFe, CoFeNi and combinations and laminates thereof.44. The sensor of claim 34 wherein the ferromagnetic free layer is abilayer comprising a layer of CoFe of thickness between approximately 5and 15 angstroms, where 10 angstroms is preferred, on which is formed alayer of NiFe of thickness between approximately 15 and 30 angstroms,where approximately 20 angstroms is preferred.
 45. The sensor of claim36 wherein the non-magnetic anti ferromagnetically coupling layer is alayer of Ru formed to a thickness of between approximately 7 and 9angstroms with approximately 7.5 angstroms being preferred.
 46. Thesensor of claim 36 wherein the non-magnetic antiferromagneticallycoupling layer is a layer of Rh formed to a thickness of betweenapproximately 4 and 6 angstroms with approximately 5 angstroms beingpreferred.
 47. The sensor of claim 34 wherein the patternedferromagnetic transversely biasing layer is a layer of CoFe formed to athickness between approximately 10 and 25 angstroms with approximately15 angstroms being preferred.
 48. The sensor of claim 49 wherein saidferromagnetic free layer and said ferromagnetic transversely biasinglayer are antiferromagnetically coupled by said antiferromagneticallycoupling layer and are transversely magnetized in antiparalleldirections.
 49. The sensor of claim 34 wherein the secondantiferromagnetic pinning layer is a layer of MnPt formed to a thicknessbetween approximately 80 and 150 angstroms, with approximately 40angstroms being preferred.
 50. The sensor of claim 34 wherein the seedlayer is a layer of NiCr formed to a thickness of between approximately50 and 65 angstroms, but where approximately 60 angstroms is preferred.51. A method for fabricating a patterned, synthetic, transverselyexchange biased GMR sensor with narrow effective trackwidth comprising:providing a substrate; forming a seed layer on said substrate; forming afirst layer of antiferromagnetic material on the seed layer, said layerof antiferromagnetic material being a pinning layer; forming a syntheticantiferromagnetic pinned layer on said first antiferromagnetic pinninglayer; forming a non-magnetic spacer layer on said pinned layer; forminga ferromagnetic free layer on said non-magnetic spacer layer; forming anon-magnetic antiferromagnetically coupling layer on said ferromagneticfree layer; forming a ferromagnetic, longitudinal biasing layer on saidcoupling layer, whereby said free layer, coupling layer and biasinglayer comprise a synthetic antiferromagnetic configuration; forming asecond antiferromagnetic pinning layer on said longitudinal biasinglayer; forming a conductive lead layer on said antiferromagnetic layer;annealing the resulting structure for an annealing time, at an annealingtemperature and in an external magnetic field; removing, by an etchingprocess, a central portion of said conductive lead layer and the portionof said second antiferromagnetic pinning layer directly beneath saidcentral portion, exposing, thereby, an upper surface of saidlongitudinal biasing layer beneath said pinning layer and forming,thereby, two discrete, disconnected and laterally separated segments,laterally and symmetrically disposed to either side of said longitudinalbiasing layer and separated by the desired physical trackwidth of saidsensor; oxidizing the exposed portion of said ferromagnetic longitudinalbiasing layer, said oxidation extending the entire width and thicknessof said exposed portion and destroying the ferromagnetic properties ofsaid layer and said oxidation being stopped by the upper surface of saidnon-magnetic antiferromagnetically coupling layer.
 52. The method ofclaim 53 wherein the seed layer is a layer of NiCr formed to a thicknessof between approximately 50 and 65 angstroms, but where approximately 60angstroms is preferred.
 53. The method of claim 51 wherein the first andsecond antiferromagnetic layers are layers of the same antiferromagneticmaterial and said material is chosen from the group of antiferromagneticmaterials consisting of PtMn, IrMn, NiMn, PdPtMn and FeMn.
 54. Themethod of claim 53 wherein the first antiferromagnetic layer is a layerof PtMn and is formed to a thickness of between approximately 80 and 150angstroms, but preferably approximately 100 angstroms.
 55. The method ofclaim 51 wherein the synthetic antiferromagnetic pinned layer is atrilayer comprising a first and second ferromagnetic layer separated bya non-magnetic antiferromagnetically coupling layer.
 56. The method ofclaim 55 wherein the first and second ferromagnetic layers are layers offerromagnetic material chosen from the group consisting of CoFe, NiFeand CoFeNi.
 57. The method of claim 56 wherein the non-magneticantiferromagnetically coupling layer is a layer of Ru or a layer of Rh.58. The method of claim 55 wherein the synthetic antiferromagneticpinned layer is a trilayer comprising a first layer of CoFe, formed to athickness of between approximately 12 and 20 angstroms with 15 angstromsbeing preferred and a second layer of CoFe formed to a thickness ofbetween approximately 15 and 25 angstroms with 20 angstroms beingpreferred, with a layer of Ru between said layers of thickness betweenapproximately 7 and 9 angstroms with approximately 7.5 angstroms beingpreferred.
 59. The method of claim 55 wherein the syntheticantiferromagnetic pinned layer is a trilayer comprising a first layer ofCoFe, formed to a thickness of between approximately 15 and 20 angstromswith 15 angstroms being preferred and a second layer of CoFe formed to athickness of between approximately 15 and 25 angstroms withapproximately 20 angstroms being preferred, with a layer of Rh betweensaid layers of thickness between approximately 4 and 6 angstroms with 5angstroms being preferred.
 60. The method of claim 51 wherein thenon-magnetic spacer layer is a layer of Cu formed to a thickness ofbetween approximately 16 and 25 angstroms, with approximately 18angstroms being preferred.
 61. The method of claim 51 wherein theferromagnetic free layer is a layer of ferromagnetic material chosenfrom the group consisting of CoFe, NiFe, alloys thereof and laminatesthereof.
 62. The method of claim 51 wherein the ferromagnetic layer isformed as a bilayer comprising a first ferromagnetic layer of CoFe ofthickness between approximately 5 and 15 angstroms, but where 10angstroms is preferred, on which is formed a layer of NiFe of thicknessbetween approximately 15 and 30 angstroms, but where approximately 20angstroms is preferred.
 63. The method of claim 51 wherein thenon-magnetic antiferromagnetically coupling layer is a layer of Ruformed to a thickness of between approximately 7 and 9 angstroms, butwhere approximately 7.5 angstroms is preferred.
 64. The method of claim51 wherein the non-magnetic antiferromagnetically coupling layer is alayer of Rh formed to a thickness of between approximately 4 and 6angstroms, but where approximately 7.5 angstroms is preferred.
 65. Themethod of claim 51 wherein the ferromagnetic biasing layer is a layer ofCoFe formed to a thickness between approximately 10 and 25 angstromswith approximately 15 angstroms being preferred.
 66. The method of claim54 wherein the second antiferromagnetic layer is a layer of PtMn formedto a thickness between approximately 35 and 55 angstroms, whereapproximately 40 angstroms is preferred.
 67. The method of claim 51wherein the anneal antiferromagnetically exchange couples theferromagnetic layers of the pinned layer and sets the antiparallelmagnetizations of said ferromagnetic layers to the transverse direction,which is the direction perpendicular to the air bearing surface of thesensor and simultaneously antiferromagnetically couples theferromagnetic free layer and the ferromagnetic biasing layer and setsthe antiparallel magnetizations of said free and biasing layers also tothe transverse direction..
 68. The method of claim 53 wherein the annealis 5 hour 280° C. anneal in a transverse external magnetic field ofapproximately 10 kOe
 69. A patterned, synthetic transversely exchangebiased GMR sensor with narrow effective trackwidth comprising: asubstrate; a seed layer; a layer of antiferromagnetic material formed onthe seed layer, said antiferromagnetic layer being a pinning layer; asynthetic antiferromagnetic pinned layer formed on said firstantiferromagnetic pinning layer; a non-magnetic spacer layer formed onsaid pinned layer; a ferromagnetic free layer formed on saidnon-magnetic spacer layer; a non-magnetic antiferromagnetically couplinglayer formed on said ferromagnetic free layer; a transversely biasinglayer formed on said coupling layer, said biasing layer being formed astwo discrete, disconnected and laterally separated ferromagneticsegments, laterally and symmetrically disposed to either side of theantiferromagnetically coupling layer and defining, thereby, a physicaltrackwidth and wherein the ferromagnetic segments of said biasing layerare magnetized in opposite transverse directions and wherein each saidsegment is antiferromagnetically exchange coupled to a portion of saidfree layer beneath said segment through said antiferromagneticallycoupling layer to form a synthetic antiferromagnetic exchange biasedconfiguration having oppositely directed magnetizations at each side ofsaid configuration; a patterned antiferromagnetic pinning layer formedas two separate, disconnected segments, wherein a segment is formed oneach ferromagnetic segment of said patterned, transversely biasing layerand is coexstensive with said segment, and wherein each of saidpatterned antiferromagnetic layer segments is exchange coupled to saidtransversely biasing layer segment; a conductive lead layer formed oneach of said antiferromagnetic pinning layer segments and coextensivewith it.
 70. The sensor of claim 46 wherein the ferromagnetic free layeris a bilayer comprising a layer of CoFe of thickness betweenapproximately 5 and 15 angstroms, where 10 angstroms is preferred, onwhich is formed a layer of NiFe of thickness between approximately 15and 30 angstroms, where approximately 20 angstroms is preferred.
 71. Thesensor of claim 36 wherein the patterned ferromagnetic transverselybiasing layer is a layer of CoFe formed to a thickness betweenapproximately 10 and 25 angstroms with approximately 15 angstroms beingpreferred.
 72. The sensor of claim 69 wherein each of the patternedantiferromagnetic layer segments is a layer of IrMn formed to athickness between approximately 35 angstroms and 55 angstroms, whereapproximately 40 angstroms is preferred.
 73. A method for fabricating apatterned, synthetic transversely exchange biased GMR sensor with narroweffective trackwidth comprising: providing a substrate; forming a seedlayer on said substrate; forming a layer of antiferromagnetic materialon the seed layer, said layer of antiferromagnetic material being apinning layer; forming a synthetic antiferromagnetic pinned layer onsaid first antiferromagnetic pinning layer; forming a non-magneticspacer layer on said pinned layer; forming a ferromagnetic free layer onsaid non-magnetic spacer layer; forming a non-magneticantiferromagnetically coupling layer on said ferromagnetic free layer;forming a ferromagnetic, transversely biasing layer on said couplinglayer; magnetizing and pinning the synthetic antiferromagnetic pinnedlayer with the first antiferromagnetic pinning layer; magnetizing andantiferromagnetically pinning with a first patterned antiferromagneticpinning layer a first portion of said biasing layer in a firsttransverse direction using a first patterning and magnetizing processwhereby said first portion is magnetized and exchange coupled to a firstportion of the ferromagnetic free layer; magnetizing andantiferromagnetically pinning with a second patterned antiferromagneticpinning layer a second portion of said biasing layer in a secondtransverse direction using a second patterning and magnetizing processwhereby said second portion is magnetized in an opposite direction tosaid first portion and exchange coupled to a second portion of theferromagnetic free layer removing, by an etching process, a centralportion of said biasing layer which is situated between said pinned andmagnetized first and second portions to form a trackwidth region of thesensor; forming a conductive lead layer over each of theantiferromagnetically pinned first and second portions of thetransversely biasing layer.
 74. The method of claim 73 wherein the firstpatterning and magnetizing process comprises: forming a layer ofphotoresist material over the biasing layer; removing a portion of saidphotoresist material to expose a portion of the biasing layer extendinglongitudinally from one lateral edge of the layer, less than half thelongitudinal width of the layer; cleaning said exposed portion with anetching process; depositing additional ferromagnetic material to restoreany ferromagnetic material removed by the etching process; forming alayer of antiferromagnetic material over said exposed portion to serveas a pinning layer; annealing the structure so formed at a firstannealing temperature for a first annealing time in a first transversemagnetic field directed in a first direction; removing the remainingphotoresist.
 75. The method of claim 73 wherein the second patterningand magnetizing process comprises: forming a layer of photoresistmaterial over the biasing layer; removing a portion of said photoresistmaterial having the same approximate dimensions as the layer removed inthe first patterning and magnetizing process, but symmetrically disposedon the opposite lateral end of the biasing layer; cleaning said exposedportion with an etching process; depositing additional ferromagneticmaterial to restore any ferromagnetic material removed by the etchingprocess; forming a layer of antiferromagnetic material over said exposedportion to serve as a pinning layer; annealing the structure so formedat a second annealing temperature for a second annealing time in asecond transverse magnetic field oppositely directed to the firsttransverse magnetic field of the first patterning and magnetizingprocess; removing any remaining photoresist from the structure soformed;
 76. The process of claim 74 wherein the layer ofantiferromagnetic material is a layer of IrMn deposited to a thicknessof between approximately 35 and 55 angstroms with approximately 40angstroms being preferred.
 77. The process of claim 75 wherein the layerof antiferromagnetic material is a layer of IrMn deposited to athickness of between approximately 35 and 55 angstroms withapproximately 40 angstroms being preferred.
 78. The process of claim 76wherein the first anneal is for between approximately 30 and 60 minutesbut where approximately 30 minutes is preferred, at a temperature ofbetween approximately 250° C. and 280° C., but where 250° C. ispreferred and with a magnetic field of between approximately 250 and 500Oe but where 250 Oe is preferred.
 79. The process of claim 77 whereinthe second anneal is for between approximately 30 and 60 minutes butwhere approximately 30 minutes is preferred, at a temperature of betweenapproximately 250° C. and 280° C., but where 250° C. is preferred andwith a magnetic field of between approximately 250 and 500 Oe but where250 Oe is preferred.